1. Field of the Invention
This present invention relates to a hinge apparatus, and more particularly to a hinge apparatus with a damper for smoothly opening or closing a foldable electronic device.
2. The Related Art
As the development of modern mobile communication industry, portable electronic devices such as cellular phones, notebook computers and personal digital assistants etc. are become more and more popular. Thereinto, many of the portable electronic devices have a function of displaying image. In order to display image as distinctly as possible, screens of the portable electronic devices need to be designed as big as possible. But it is not convenient to carry the portable electronic device with a big screen. That is, the required big screen and the required small size of the portable electronic device are self-contradictory. To solve the problem, the foldable electronic devices have been developed. Generally, the foldable electronic device has a cover which is used as a screen of the foldable electronic device, and a main body which is joined together with the cover by a hinge allowing the cover to be unfolded or folded from the main body.
Referring to FIG. 1, a traditional hinge includes a housing 3, a sliding cam 5, a rotatable cam 6, a spring 4, a shaft 7, an E-ring 8 and a cap 9. The sliding cam 5, the rotatable cam 6 and the spring 4 are received in the housing 3. A lower end of the sliding cam 5 defines two concave portions 51. An upper end of the rotatable cam 6 defines two pushing portions 61 for mating the two concave portions 51, and a lower end of the rotatable cam 6 extends out from the housing 3. A lower end of the spring 4 is fixed on the sliding cam 5, and an opposite end of the spring 4 is mounted on the cap 9 which plugs an upper end of the housing 3. The shaft 7 passes through the rotatable cam 6, the sliding cam 5, the spring 4 and the cap 9 and is locked by the E-ring 8. If the foldable electronic device needs opening, a user firstly unfolds the cover from the main body of the foldable electronic device at an angle. The force that the user provides pushes the pushing portions 61 to the top of the concave portions 51. At the same time, the sliding cam 5 is compelled to slide toward the upper end of the housing 3, and the spring 4 is compressed. Then, the user stops acting on the foldable electronic device, and the elastic force of the spring 4 drives the foldable electronic device opened fully.
However, the process that the compressed spring 4 drives the foldable electronic device opened fully is too quickly. Therefore, an impact is produced between the cover and the main body, so the foldable electronic device is easy to be broken or damaged.